Which term describes the frequency of an event occurring over time?

The correct term that describes the frequency of an event occurring over time is "temporal." This term relates specifically to time and is often used in contexts involving the timing and frequency of events. In various fields, including science and social studies, understanding how often an event happens and correlating it with different timeframes is essential.

Chronological pertains to the arrangement of events in the order they occurred, which focuses more on the sequence rather than the frequency of events. Sequential refers to a specific order in which something follows another, again emphasizing the progression of events rather than how often they occur. Descriptive typically relates to characterizing or outlining features of an event or phenomenon, without implications about time or frequency.

Thus, "temporal" is the most appropriate choice, as it directly relates to time and frequency.